Manufacture of gasoline



Jan. 6, 19,42.T "H. v. ATWELL ErAl.

MANUFACTUR -oF GAsoLINE FledJan'. 27, 1939 mmZmOZOU No.

mmmozool HAROLDV ATwELL FRANK H BRUNER INVENTORS ATTOR Peiented Jen. 6,1942

UNITED STATES PATENT oEEicE j yazc'azmz D v .,MANUFAcTUnEor'GAsoLmE Harold V. Atweli and Frank Il. Bruner, Beacon,

N. Y., assignors, by mesne assignments, -to The York, N. Y., a corporation- Texas Company, New of Delaware l Application January 27, 1939, Serial No. 253,052

14 Claims. (Cl. 196 10) This inventionrelates tothe manufacture of high antiknock gasoline ,hydrocarbons by the alkylation or condensation of low boiling iso. parailins, such as isobutane or -isopentane, with olens, particularly normally gaseous olens or .polymers thereof. The invention has to do par 'ticularly with improvements in the alkylatlon of normally gaseous vhydrocarbons containing propylene, whereby the efficiency. and facility ofthe oil absorbent but the separation of the propylene from the propane is4 more 'diilicult It isadvantageous, to separate from the charge to an alkylalun tion system the propane which is often present in relatively large amounts in the C3 fraction, since it would build up in the system .and cause undue dilution oi the reactive constituents. We have found that the propylene may be advantageously absorbed in concentrated sulfuric acid without substantial polymerization, providing there are no large amount of butenes present. The resulting mixture ofacid and absorbed propylene is suitable for use in the alkylation operation.

It is vdesirable to'carry out the alkylation of pounds.

'In theollowing description, the invention is described in connection with thetreatment of gases from an adjacent cracking still but it is to be understood that suitable unsaturated gaseous hydrocarbons from any lsource may be treated. In the modication'shown in the drawing, a cracked unstabilized naphtha from an adjacent cracking still is introduced through the line l to a cracking plant accumulator ordepropanizer 2. This accumulator may be connected direuy with the cracking sau whereby 4 substantially allthe gases and liquids from the still arevcollected; .or the accumulator may be for the purpose of receiving distillate from a receiver in which all or a portion of the ilxed gases, such as hydrogen, methane and C i hydrocarbons have been released. It is intended that the product collected in the accumulator 2 contain substantially all of the C3 and C4 hydrocarbons.

The pressure maintained on the accumulator 2 may depend on' the volatility of the stabilized n aphtha desired. If a stabilized n aphtha of approximately 10j pounds Reid vapor pressurel is intended to be produced, then the laccumulator may be under a pressure of approximately 50 If a. stabilized naphtha of about `14 pounds Reid vapor pressure is intended to be produced,- then the .accumulator drum may vadvantageously be maintained under a higher pressure, for example about 150 pounds. When the isobutane with normally gaseous oleflns in the liquid phase and this can be done at ordinary temperatures with relatively. lo'w superatmos pheric pressure,.in the case of C4 hydrocarbons.V When large amounts of Ca hydrocarbons are used, however, greater' difliculty is encountered in maintaining the liquid phase due tothe volatility of the'mixture, particularly when large amounts of propane are present. It has been found that an advantageous method of operation is to absorb the propylene in concentrated sulfuric acid and then introduce the mixture into the system under approximately the liquid phase conditions which are used when alkylating 'substantially only C4 hydrocarbons.

40 lator 2 contain substantial amounts of C4 hydrol with concentrated sulfuric acid for thepurpose The invention Will be more fully'underrtood from the following description read in connection with the accompanying drawing which shows` a diagrammatical sketch of one form of apparatus for carrying out the process ofthe invention. gases substantially all the C4 hydrocarbons from accumulator is maintained under lower pressure,l

the gaseous hydrocarbons', released therefrom through vapor line 5 will contain substantial v amounts of Crhydrocarbons in addition to the Ca hydrocarbons, Whereas if the higher pressure is maintained on the accumulator drum, the gases withdrawn through the line li 'may be tially free from C4 hydrocarbons.

.In case the gases removed from the accumuclarbons, it is advantageous to separatethe C4 hydrocarbons from the4 Ca hydrocarbons since it.

has been found that substantial amounts of C4 hydrocarbons cause undue polymerization or hydropolymerization'when the gases are contacted of absorbing propylene. If the gases contain amounts of` C4 hydrocarbons, particularly butenes, in excessl of about 5%, then the gases are passed through lines 5 `and 6 to an absorber il` wherein they are scrubbed with an absorbent oil such-'as mineral seal, introduced into theupperl portion of the absorberv through, the line I6. In ,the absorber it is intended to' scrub out froml the substanthe Ca hydrocarbons which are released from the upper portion of the absorber through the line 9 troduced into the stripper i wherein the absorbed hydrocarbons are distilled from the absorbent which is withdrawn in a lean condition from the lower portion of the stripper I5 and reintroduced into the absorber through the line i6. The distilled C4 hydrocarbons are withdrawn from the upper portion of the stripper lthrough the line i8, and conducted to the condenser 20. referred to hereinafter.

In case the gases removed fromthe accumulator 2 through the line 5 contain relatively small amounts of C4 hydrocarbons, particularly butenes, for example about 5% or less, these gases may be conducted directly to the absorber l2 through the lines2l and i0. When the gases contain such small amounts of butenes, it has been found that propylene may be absorbed from the gases by concentrated sulfuric acid without substantial polymerization or hydropolymerization of the olens.

In the absorber l2 the gases are scrubbed with sulfuric acid introduced into the upper portion thereof through the line 22. This acid should be of yat least 90% concentration, and preferably about.94% or stronger. A temperature suitable for the absorption of propylene, preferably under 30 C., is maintained in the' absorber. The propylene is substantially entirely absorbed by the acid and the unabsorbed gases, principally propane, are released from the top of the absorber through the line 23. The mixture of acid and absorbed propylene is withdrawn from the lower portion of the absorber, and passed through the line 25, containing a pump 28, to a reactor 28.

A cracked naphtha containing C4 hydrocarbons is withdrawn from the accumulator 2` and 'Q passed through the line 30 to the stabilizer 32.

In the stabilizer the naphtha is stabilized to substantially commercial gasoline specifications, although all or any portion of the C4 hydrocarbons may be removed and in case the stabilized naphtha is decient in volatility, normal butane may be addedthereto to brlngup the volatility.

The stabilized naphtha is withdrawn from the lower portion of the stabilizer through the line 33. The normally gaseous hydrocarbons separated from the naphtha in the stabilizer are withdrawn from` the upper portion thereof through the line 35 and may be passed to the absorber 8. The treatment of these gases in the absorber 8 is desirable in case the gases contain any substantial lamount of C: hydrocarbons whereby a yseparation of the C3 hydrocarbons from the C4 is accomplished in the absorber. It the gaseous hydrocarbons removed from the top of the stabilizer contain substantially only.C4 hydrocarbons, then they may be conducted through the line 88 directly to the condenser 20,V

referred to heretofore. In the condenser the C4 azeasoa or condensation of isobutane with the olens,

including butenes and propylene, take vplace in the presence of sulfuric acid as a catalyst. The conditions suitablefor such reaction are temperatures of about to 100 F. and preferably about to 70 F. The products should be intimately contacted, for example by suitable stirring mechanism, such as the stirrer d3. Sufn cient -pressure is held in the reactor to maintain the hydrocarbons substantially in the liquid phase. The sulfuric acid should be of about 90 to 100% strength, and preferably about 94 to 98% concentration. The amount of acid should be sufficient to provide an acid dosage of about equal to that of the oleins by Weight. The acid from the absorber I2-may be of sufficient strength and volume to satisfy the requirements in the reactor 28, although it is contemplated that fresh or recycle acid in suitable amount and in sufcient strength may be used to provide the volume and concentration requirements of the acid in the reactor. A relatively high ratio of isobutane to olefinfor example between about 3:1 and 5:1, is desirable and, if it is necessary to add additional isobutane other than that contained in the C4 hydrocarbons from the receiver 38, this additional isobutane may be introduced through the line 45 by the pump 46.

The reaction products are transferred from the reactor 28 through the line -48 to a settler 50 wherein the acid is allowed to settle out in the lower portion thereof, and may be withdrawn neutralizer 55, wherein the hydrocarbons are hydrocarbons are cooled and condensed and the' condensate passed through the run-down line 81 to a receiver I8. The products collecting in the receiver 38, including normal butane, lsobutane and isobutenes, are conducted through the line 4l in which is located a pump 4i, to the reactor 28.

In thejreactor 28 it is intended that alkylation contacted with a neutralizing agent, such as aqueous caustic alkali or soda, introduced into the upper portion of the neutralizer through the line 56 by the pump 58. In the neutralizer 55 the hydrocarbons are intimately contacted with a neutralizer and any acidity removed. The spent alkali is withdrawn from the lower portion of the neutralizer through the line and may be recycled, if desired. The neutralized hydrocarbons are Withdrawn from the upper portion of the neutralizer through the line 6I to a stabil- 'izer 82. If necessary, a settler may be provided between the neutralizer 55 and the stabilizer 62 to separate the spent alkali.

In the stabilizer 62 the hydrocarbons are stabilized to produce a liquid product containing sufilcient butane to satisfy the volatility requirements of the gasoline product when the latter is separated therefrom. The excess butane, togetherA with other C4 hydrocarbons is removed overhead from the stabilizer and conducted through the line io fractionator 85. In the fractionator a separation is made between the isobutane and the normal butane. The normal butane is condensed and collected as. a liquid in the lower portion of the fractionator and may be withdrawn from the bottom thereof through the line 88 and discharged from' thesystem or passed 'through the line 81 by the pump 8l for blending with the stabilized naphtha withdrawn from the stabilizer 82. 'I'he isobut'lieA is withf drawn from the top of the frazionator I5 I through the line 10 and 'compressed'y the compressor 1|. 'I'he compressed hydrocarbons are cooled in the cooler 12 sufllciently to eiIect con-` densation thereof and the liquids are passedthrough the line 13 to further reaction.

The liquids withdrawn from the'bottomof the stabilizer B2 are passed through the line 15 by the pump 16 to fractionatorfl wherein the product is fractionally distilled to separate a product boiling' within the gasoline boiling point range. The hydrocarbons of higher boiling point than gasoline are withdrawn as bottoms from the lower portion of the fractionator l8through the line 80. The gasoline vapors are conducted 'overhead from the fractionator 18 through the line 8i and condenser 82 to a receiver 84. The

product collecting in the receiver 84 consists essentiallyof saturated hydrocarbons of high antiknock value, and suitable for the manufacture of gasoline motor fuel.

As'an example of the operation of the invention, cracked naphtha from a cracking still is collected in an/y accumulatonmaintained under a pressure of about 50 pounds per square inch.

-Gases and vapors are released from thel accumulator and passed to an absorber wherein they rare scrubbed with an Aabsorbent oil Vtot remove substantially all the C4 hydrocarbons, which are later distilled from the rich absorbent. The unabsorbed hydrocarbons'from the absorber are passed to an acid absorber wherein they are .contacted with sulfuric -acid of about 94% con;

centration, whereby the proylene is absorbed.

` The mixture of acid and absorbed propylene is then charged to an alkylation reactor.

.tha is withdrawn from the cracking plant accu- A naphf mulator and charged to a stabilizer from which a stabilized naphtha of about gasoline volatility' is produced. Vapors from the stabilizer consist-4 ing essentially of C4 'hydrocarbons are condensed to form a liquid Cr hydrocarbon fraction which is also charged to the alkylation reactor. Sumcient isobutane is charged to the reactor to maintain an'overall ratio of isobutane to olensain The hydrocarbons inthe reactor are intimately contacted in 'the liquid phase with the acid at va temperature of about the feed of about 3:1.

65 F. for sufficient time to effect substantial alkylation ci the isobutane with the butenes and propylene. The acid is removed from the reaction products and the hydrocarbonsneutralized. The product is'then stabilized to produce aliquid fraction of substantially gasoline boiling point range. and volatility. The overhead from the stabilizerv is fractionated to separate out the normal butane from the isobutane and the isobutane recycled to the alkylation operation. A gasoline product corresponding to a yield of about 150% based on the oleiins, and having an octane value of about 85 is obtained.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may

be made without departing from the spirit and scope thereof, and therefor` only such limitations should be imposed as are indicated in the appended claims.

We claim:

L A process for the manufacture of high antiknock gasoline hydrocarbons, which comprises absorbing propylene in concentrated sulfuric.

acid of alkylation strength, and then treating the mixture with isobutane and a butene in the liquid phase under alkylating conditions effective the reactor 28 to undergo 2. A process for the manufacture of high anti.- knock gasoline hydrocarbons, which comprises forming a mixture o f propylene and concentrated sulfuric acid of alkylation strength, then treating the mixture with isobutane and butenes in the liquid phase under alkylating conditions effective for the alkylation ofsaid butenes by the isobutane, whereby the absorbed propylene is alsoalkylated by the isobutane under these conditions to produce saturated hydrocarbons `of high anti-knock Avalue boiling within the gasoline boiling range.

3. A process for the manufacture of high anti- Aknock gasoline hydrocarbons, which comprises absorbing propylene in sulfuric acid without substantial polymerization thereof vby contacting gaseous propylene with concentrated sulfuricl acid, then alkylating isobutane and butenes, in

the 4liquid phase, with the sulfuric acid and propylene mixture, while maintaining the concentration of the acid in the alkylation zone at about 90 to 98%.

4. A process for the manufacture of high antiknock gasoline hydrocarbons, which comprises treating under alkylating conditions C4 hydrocarbons including butenes and isobutane in the liquid phase atabout atmospheric temperatures witha solution of propylene absorbed in concentrated sulfuric acidl of alkylation strength and separating fromthel reactionmixture saturated, high antiknock hydrocarbons within the butane and in the presence of a C4 olefin, whereb'y the .absorbed-propylene and the C4 Aolefin are -alkylated by the isobutane toform high -antid knocksaturated hydrocarbons within the gasoline boiling range.

6. A Vprocess according to claim 5 in which the amount of butenes in the hydrocarbon mixture is not in excess of about 5%.

7. A process for the-manufacture of 'high antiknock vgasoline hydrocarbons, Awhich comprises treating a. gas-containing mainly propylene-.and

, sorbed propylene and butenes to form butenes in sufficiently small amounts that substantially no polymerization occurs with conc'entrated sulfuric acidto absorb .the propylene,

-then contacting the acid mixture'under alkylating conditions with butenes and excess isobutane whereby the isobutane is alkylated by the abhigh antiknockfgasoline hydrocarbons.

8. A process for the manufacture of high antiv knoclr gasoline hydrocarbons, 'which comprises separating unsaturated normally gaseous nydrov bons into a light fraction containing mainly hydrocarbons of -less than ,4 carbon atoms and a heavy fraction containing' mainly hydrocarbons of 4 carbon atoms including. butenes. separating for the alkylation of said butene by the lsobu-T tane, whereby the labsorbed propylene vis also alkylated by the isobutane under these conditions to produce saturated hydrocarbons of high ,antiknock value. within the vgasoline boiling range.

propylene from" the light fraction by absorption in' concentrated sulfuric acid, then contacting under alkylating conditions said absorbed propylene. vand said heavy 'fractionin the presence of vexcess isobutane and concentrated sulfuricacid of alkylation-strength whereby the isobutane is alkylated with the absorbed propylene and butenes, and separating from the reaction products gasoline hydrocarbons of high antiknock value.

9. A process for the manufacture of high antiknock gasoline hydrocarbons, which comprises fractionating unsaturated normally gaseous hydrocarbons into a light fraction predominatng in C3 hydrocarbons and a heavy fraction predominating in C4 hydrocarbons, scrubbing' the light fraction with sulfuric acid to absorb propylene, then intimately contacting under alkylating conditions the acid mixture with said heavy fraction while maintaining an excess of isobutane and acid of alkylation strength in the' reactionl mixture whereby the isobutane is condensed with the absorbed propylene and C4 olefins to form high antiknock gasoline hydrocarbons and separating said gasoline hydrocarbons from the reaction products.

l0. A process for the manufacture of high antiknock gasoline hydrocarbons, which comprises stabilizing a cracked distillate to produce a light gaseous fraction containing mainly hydrocarbons of less than 4 carbon atoms together with some hydrocarbons of 4 carbon atoms, further stabilizing the distillate to separate a heavy gaseous fraction consisting essentially of hydrocarbons of 4 carbon atoms, scrubbing said light fraction with an oil absorbent to separate hydrocarbons of 4 carbon atoms, further scrubbing the light fraction with concentrated sulfuric acid to separate propylene, contacting under alkylating conditions'the acid and propylene mixture with theA hydrocarbons of 4 carbon atoms while maintaining the acid at alkylation strength and an excess of isobtuane in the mixture, whereby the isobutane is alkylated by the absorbed propylene and C4 olens to form high antiknock gasoline v hydrocarbons, and separating said gasoline hydrocarbons from the reaction products. 11. A process for the manufacture of hig antiknock gasoline hydrocarbons, which comprises separating from a. .cracked distillate a light gaseous hydrocarbon fraction consisting essentially of hydrocarbons of 3 carbon" atoms and lighter including propylene and not more than a small amount of C4 hydrocarbons, stabilizing the resulting cracked distillate to separate therefrom as a stabilizer distillate atfleast a portion of the Cd hydrocarbons including butenes and butanes,

treating the light hydrocarbon fraction with concentrated sulfuric acid to absorb the propylene, charging the resulting mixture of sulfuric acid and absorbed propylene to a liquid phase alkylation operation, also charging to the alkylation unit said stabilizer distillate and sufiicient isobutane to bring the ratio of isobutane to olefins in the combined charge to the aikylation operation to at least 1:1, intimately contacting the hydrocarbons with concentrated sulfuric acid of alkylation strength in the alkylation operation whereby the isobutane is alkylated by the olen compounds and separating from the reaction products saturated high antiknocky hydrocarbons of gasoline boiling range.

12. A process for the manufacture of high antiknock gasoline hydrocarbons, which comprises contacting in the liquid phase under alkylating conditions, normally gaseous hydrocarbons consisting mainly of C4 hydrocarbons including butenes and isobutane with concentrated sulfuricl acid of alkylation strength in a. reaction zone, introducing into said reaction zone a mixture of propylene absorbed in concentrated sulfuric acid, maintaining in the reaction zone the isobutane in excess of the oleflns and the acid at alkylation strength whereby the isobutane is` alkylated by the absorbed propylene and butenes to form high antilmock gasoline hydrocarbons and separating said gasoline hydrocarbons from the reaction products.

13. A' process for the manufacture' of highy antiknock gasoline hydrocarbons, which comprises introducing a mixture comprising propyl, ene absorbed in strong sulfuric acid into an alkylation reaction zone containing al butene com- -pound and isobutane maintained under effective C4 liquid phase alkylating conditions, and maintaining the sulfuric acid in said zone of alkylation strength and the isobutane in molar excess' of the equivalent olen content therein, whereby the isobutane is alkylated by the absorbed propylene and butene compound to form high antiknock gasoline hydrocarbons.

14. A process for the manufacture of high anti-knock gasoline hydrocarbons, which comprises introducing a propylene-sulfuric acid absorption product into an alkylation reaction zone containing a butene compound and a low-boiling isoparaflin maintained under. eifective'Ci liquid phase alkylating conditions, and maintaining in said zone sulfuric acid of alkylation strength and the low-boiling 'isoparafiin in molar excess of the equivalent olefin content therein, whereby the low-boiling isoparaiiln isalkylated by the propylene-sulfuric acid absorption product and butene compound to form high anti-knock gasoline hydrocarbons. c l

HAROLD V. ATWELL. FRANK H. BRUNER. 

